Suction-type matrix drier with means for controlling drying time and suction



June 1, 1965 G. M CLARK 3,186,108

SUCTIONTYPE MATR Iii DRIER WITH MEANS FOR CONTROLLING DRYING TIME AND SUCTION Filed Sept. 22, 1960 3 Sheets-Sheet l Zia aw i /Z z /mhiz G- M. CLARK 3,186,108 SUCTION-TYPE MATRIX DRIER WITH MEANS FOR 5 Sheets-Sheet 2 Jaw/2Z7 fa r a/ZJZWJZ MW r SILICONE June 1,1965

CONTROLLING DRYING TIME AND SUCTION Flled Sept 22 1960 June I, 1965 Fi-led Sept. 22, 1960 SUCTION-TYPE G. M. CLARK MATRIX DRIER WITH TIMER F OR 1 LOW SUCTION [9 g? ENOID I FOR LATCH OPERATION MEANS FOR CONTROLLING DRYING TIME AND SUCTION 5 Sheets-Sheet 3 M o o- I MAKE-AND-BREAK FOR HEQTER TIMER FOR HE A TER Igg r LARY MAKE-AMP s w f o I //fl United States Patent 3,186,108 SUCTIUN-TYPE MATRIX DRIER WITH MEANS FOR CONTROLLING DRYING TIME AND SUCTIQN George M. Clark, 415 Lowell Sh, Lynnfield Center, Mass. Filed Sept. 22, 1960, Ser. No. 57,664 Claims. (Cl. 34-53) This invention relates to apparatus for drying matrices such as are used for molds in casting type plates for printing presses. -Matrices of this kind are thick sheets of moist paper pulp in one face of which the faces of set-up type are impressed. If the type plate is for a cylinder press, the matrix is then curved into semi-cylindrical shape and is dried in that shape; if the plate is for a flat press, the matrix is dried flat. Heretofore it has been customary to treat the matrix to a preliminary drying treatment at moderate temperatures to set the fibers. This is then followed by a scorching treatment to drive out substantially all of the residual moisture so that when the molten type comes in contact with the face of the matrix in the coating operation, there will be no moisture present to vaporize and spoil the casting.

According to the present invention, apparatus is employed which starts in a moderately warm condition with each matrix and builds up heat to the desired maximum at a controlled rate so that in the early stages of the process, the heating is moderate to set the fibers but then builds up to higher temperatures to complete the drying operation thoroughly.

Such apparatus can be designed to dry matrices in semicylindrical form or in fiat form.

The apparatus hereinafter described in detail is, by way of example but not limitation, designed for drying matrices in the semi-cylindrical form. It includes a number of automatic features such as the regulation of the intensity of the vacuum or suction employed to hold the matrix firmly against a concave semi-cylindrical form so that it will have the correct shape when dried. Time clocks are provided to control the periods of drying treatment and application of suction, and to shut off the apparatus when the prescribed treatment of a matrix has been completed.

Various other advantageous features of the apparatus will be apparent from the following description thereof and from the drawings, of which FIGURE 1 is an end elevation of an apparatus embodying the invention;

FIGURE 2 is a front elevation of the same with the front panel of the housing omitted to show some of the mechanism within;

FIGURE 3 is a fragmentary section, on a larger scale, on the line 3-3 of FIGURE 1;

FIGURE 4 is an enlarged perspective view of the valves used in regulating the suction applied to the matrix;

FIGURE 5 is a section, on a larger scale, on the line 5--5 of FIGURE 4;

FIGURE 6 is an exploded perspective view of supporting means for the matrix;

FIGURE 7 is an enlarged section on the line 77 of FIGURE 2, but showing the cover shut;

FIGURE 8 is a fragmentary section on the line 88 of FIGURE 7;

FIGURE 9 is a fragmentary sectional detail of the cover; and

FIGURE 10 is a wiring diagram of the circuits employed.

The apparatus shown on the drawings comprises a generally rectangular cabinet or housing 10, part of the top member 12 of which is a semi-cylindrical trough adapted to receive a matrix for treatment. As indicated in FIG- URE 7, this top member consists of a vacuum or suction box having a double wall enclosing a narrow suction chamber. The inner or upper wall 14 of the box has many perforations 15 therethrough for inflow of air into the box. From the bottom of the member or box 12 a pipe line 17 extends through a filter box 18 to a vacuum pump 21 which is driven by an electric motor 22 to which it is connected by any suitable means such as a belt 24. To keep the matrix M from direct contact with the vacuum box 12, a wire screen 26 overlies the upper wall 14 of the box. This screen has a fine mesh and a border 28 of silicone-rubber material which is resilient but which can Withstand the high temperatures to which it is subjected in use. This border seals the margins of the perforated inner wall 14 of the vacuum box 12 so that all the air entering the box 12 must come through the screen 26. If matrices of different sizes are to be processed, corresponding screen sizes are employed so that the margins of the matrix will overlap the borders 23 of the screen.

Suitable arcuate metal strips 30 are fastened to the end margins of the vacuum box 12 by screws or bolts to clamp the end borders 28 of the screen 26. The strips 30 carry adjustable stop elements 32 for the end edges of a matrix to assist in properly placing the matrix on the screen 26. The front and rear borders 28 of the screen are held in place by coil springs 34, 36 which also serve to clamp the front and rear margins of the matrix M when the latter has been inserted in the machine. Stop elements 37 are provided to position the rear edge of the matrix.

During the preliminary and final drying operations the matrix is sucked against the screen, or, more properly, pressed by atmospheric pressure against the screen, as reduced pressure is maintained in the suction box 12. The suction should be relatively light during the preliminary drying to prevent injury to the matrix when the matrix is damp and soft. A stronger suction is used after the initial stage of drying, when the matrix is mechanically stronger, to hold the matrix tightly against the semicylindrical screen so that it will be accurately shaped when bone-dry.

For regulation and control of the suction, a manifold 40 is connected into the pipe line 4-1 from the box 18 to the pump 20. This manifold has three air valves 42, i4 and 46. The valve 42 is an adjustable spring-pressed valve which determines the maximum suction in the system. The spring is adjusted to permit the valve to open to admit relief air whenever the suction in the manifold exceeds the magnitude for which the valve is set.

The valve L4 is a bleeder valve to prevent the constantly running pump from building up excessive suction such as would have to be relieved constantly or frequently by the valve 42. As indicated in FIGURE 5, the valve 44- may be of the stop-cock type by which the size of the opening for the inflow of air can be readily regulated. For this purpose the angular position of the valve plug 48 can be manually adjusted by turning the stem 50 (FIGURE 2).

The valve 46 is an on-and-off relief valve including a rotatable cap 52 with a number of holes 54 therein which register with similar holes through an inner plate (not shown) to admit enough air into the system, together with the bleeder valve 44, to keep the suction at a low value. A spring 56 yieldingly maintains the valve in its open position. In the operation of the apparatus, the valve is closed by a solenoid 58, whereupon the suction builds up to the maximum permitted by the bleeder valve 44 and spring valve 42.

As the bleeder valve 44 is always open, it is connected by a pipe 59 to an inlet manifold 60 consisting of a horizontal pipe with closed ends in front of the suction box 14. The manifold 60 has a row of openings 62 which suck in whatever gases are driven from the matrix when it is strongly heated. These gases pass through the pump 20 and may be discharged outside of the building, if desired, by any convenient means, not shown, leading from the pump.

The heat employed to dry out a matrixmounted against the semi-cylindrical screen 26 is supplied by means of a semi-cylindrical heater 66 which is rockably supported by a top cover 68 which is hinged at 70 to the rear edge of the cabinet so as to swing down from a raised or open position to a closed position in which the heater is in the concavity of the trough-like suction box 12. The heater comprises a top plate 72 with semicircular end plates 74 extending down therefrom. Between these end plates a series of parallel elongated heating units 76 are carried in semi-cylindrical array by semi-circular bars 78 to which they are bolted as indicated in FIGURE 9 for ready removal and replacement. The bars 78 are fastened at their ends to the under side of the top plate 72 of the heater. In the example shown on the drawings, thirteen units 76 are provided, these being supported in such a manner that when the cover is closed, as shown in FIGURE 7, the series of units 76 will be coaxial with the matrix on the screen 26 and the units themselves will be spaced an inch or so from the matrix and about 1 /2 inches from each other, these figures being given by way of example and not limitation. Above the series of heating units 76 and uniformly spaced an inch or so therefrom is a polished reflector 80 which is supported by the top plate 72 of the heater. Each heating unit 76 is a tube having three side faces and a triangular cross section and containing the customary resistance coil 81. The units are mounted so that one side of each unit faces outward away from the reflector 80, the other sides of each unit facing the reflector obliquely. The heat radiated from the outward faces of the units goes directly to the matrix M while the heat radiated from the other faces of the units is reflected at various angles by the reflector to pass through the spaces between the units to the matrix M so that the heat radiation is distributed with satisfactory uniformity over the surface of the matrix as is evidenced by the uniformity of discoloration of the matrix surface resulting from the scorching operation.

The top cover 68 from which the heater depends comprises a rectangular frame, including a handle 82 in front by which the cover can be manually swung down to its closed position, and a top plate 83 on the frame which is preferably apertured or perforated.

When the cover 68 is swung down to its closed position as determined by adjustable stops 84, a lug or pin 85 on an arm 86 (FIGURES 1 and 2) at one end of the frame 68 is caught and held by a latch member 88 pivotally mounted on an end wall of the cabinet 10 and operable by a solenoid 89 to release the cover 68 and the heater 66 carried thereby. When they are thus released, the cover is swung up to its open position by a counterweight 90, the upward swing being checked by a conventional dashpot (not shown). This raises the heater 66 out of the trough in which the matrix is mounted.

When a matrix M is to be inserted in the machine, the cover is in its raised position as shown in FIGURES 1 and 2. The vacuum pump is started as hereinafter described to provide suction at the screen to assist in placing the matrix properly. The rear margin of the matrix is pushed up under the spring 36 until the edge meets the stops 37 and an end edge of the matrix is made to engage the stops 32. The suction then holds the matrix smooth against the screen whereupon the cover and heater are swung down to the position indicated in FIGURE 7, and the heating units are automatically activated to dry out the matrix. As the cover approaches its closed position, two fingers 94 on the support frame of the cover 68 press down on the spring 34 near the ends thereof, causing the spring to overlie the front margin of the matrix, as indicated in FIGURES 7 and 8, and to hold that margin fiat so that it will not cockle when the matrix dries.

Provision is made for automatic control of the suction and heating mechanisms so that when the cover 68 is swung down and held by the latch 88, the suction and heat are automatically applied for predetermined periods and at predetermined values through a complete cycle which is terminated by actuation of the latch 88 to release the cover 68 so that it is swung up with the heater 66 by the counterweight. This shuts off the power.

Circuits for controlling the operations are indicated in FIGURE 10. To power lines 100, 102, four circuits are connected, each of which includes a microswitch operated by closing and opening movements of the cover 68. The four microswitches 104, 106, 108, are indicated in FIGURES 2 and 10.

The microswitch 104 is normally closed, i.e. when the cover 68 is up. In series with this microswitch is a normally open switch 112 operated by a starter button, a normally closed switch 114 operated by a stop button, and the vacuum pump motor 22. Thus by pressing the starter button, the pump can be started when the cover is up to provide suction through the screen 26. The switch 112 is magnetically held closed until the circuit is broken. The suction assists the operator in placing the moist matrix smoothly on the screen. When the cover 68 is swung down to its closed position, the switch 104 is thereby opened to break this circuit, whereupon the starter button switch 112 snaps to its open position by means not shown but well known in the art.

The microswitch 106 is normally open and is in series with the pump motor 22. It is also in series with a timer A. This includes a conductor arm 116 which is swung about one of its ends by a motor 118, the other end of the arm being normally in contact with an arcuate element 120 which is in series with the motor 118. When the arm 116 is swung by the motor 118 until it moves off the end of the contact element 120, the circuit through the motor 118 is broken and the motor stops. In moving from contact with the element 120, the arm makes contact with another element 122, thus closing a circuit to a second timer B comprising a conductor arm 124 swingable about an end thereof by a motor 126. The other end of the arm 124 touches an arcuate element 128 which is in series with the motor 126 so that when the arm moves out of contact with the element 128, the motor 126 stops. In doing so, the arm 128 makes contact with another element 130 which is in series with the latchoperating solenoid 89 to release the cover 68 and permit it to swing open. This opens the microswitch 106 and stops the pump motor 22.

Also in series with the contact element 122 of the timer A is the solenoid 58 which when energized holds the air valve 46 shut, so that while the arm 116 is in contact with the element 122, the valve 46 is held shut and the suction on the matrix is high during the scorching period of a cycle of operations.

The microswitch 108 is normally open and is in series with a timer C which includes a conductor arm 132 swingable about one end thereof by a motor 134, the other end of the arm 132 being in contact with an arcuate element 136. When the microswitch 108 is closed by the closing of the cover 68, the motor 134- starts to swing the arm 132 so that the free end thereof travels along the conductor strip 136 until it runs off the end of the strip and breaks the circuit. The strip is connected to a clock D which automatically makes and breaks, at regular intervals which can be regulated, a circuit through a, relay 138 by which current through the heating units 76 is turned on and off. By using the clock D to interrupt the current to the heating units 76 at intervals, a prompt initial response is obtained when the heater circuit is turned on, but the interruptions slow the heating up of the heating units to give the fibers of the matrix a chance to set, and then prevent excessive heating of the heater units during the scorching process.

A similar clock E is connected to the power line through a normally closed switch 110. This clock is connected to the relay 13S and may be operated as desired when the cover 68 is up to keep the heating units 76 properly warmed for the resumption of operations following a considerable inactive period such as a noonhour break. When the cover 68 is down, the switch 110 is open so that this clock does not interfere with the operation of the clock D.

The operation of the mechanism as a whole is as follows. At the beginning of a day, the machine is preferably run through a cycle with no matrix therein, so as to warm up the heating units '76. With the cover 68 raised, the starter button 112 is pressed to start the pump motor 22, thus creating a suction through the perforations of the box 12. A matrix M is then put into the trough and its rear margin is pushed under the spring 36, the left side edge of the matrix being placed against the stop elements 32. With the help of the suction, the matrix is smoothly laid on the screen 26. The cover is then swung down to its closed position in which it is held by the engagement of the latch 88 on the pin 85. This movement closes microswitches 105 and 108, starting timers A and C, and opens microswitches 104 and 110, breaking the circuit through the starter button 112 which thereupon snaps to its open position, and opening the circuit through the timer E.

The closing of the microswitch 106 closes a circuit through the pump motor 22 and starts the motor 118 in timer A. The latter measures a time interval during which a low vacuum is maintained in the suction box 12, the valve 46 being held open by the spring 56. When the arm 116 moves from the contact element 129 to the element 122, the solenoid 58 is energized to close the valve 46 so that a high vacuum is thereafter maintained in the suction box 12. At the same time, the timer B is started. This timer measures a predetermined time interval at the conclusion of which the arm 124 reaches the contact point 130 and closes a circuit to energize the solenoid 89 which trips the latch 88 and permits the counterweight 90 to swing the cover 68 up to its open position, thus ending a cycle of operations.

In the meantime, at the beginning of the cycle, the closing of the cover 68 closes the microswitch 108 which starts operation of the timer C and the clock D so that current is sent through the heating units 7 6 intermittently for a given interval of time determined by the setting of the timer C. The timer C is preferably set to shut oif the heating circuit before the end of the operating cycle so that an interval elapses before the cover is released to its open position. The opening of the cover opens the microswitches 106 and 108 and closes the microswitches 104 and 119. The timers are constructed so that when the circuits to them are broken, the arms which have advanced snap back to their starting positions so that the timers are ready for the next cycle of operations.

I claim:

1. Matrix drying mechanism comprising a frame, a suction box on said frame having a perforated wall, a wire screen fitted on said perforated wall, a cover member hinged to said frame and swingable from an open position to a closed position over said screen, a pump for drawing air from said box, a motor operatively connected to said pump, a circuit connecting said motor to a source of power, a normally open microswitch in said circuit, said switch being closable by closing movement of said cover, a manually operable starter switch on said frame, a normally closed microswitch operable by closing movement of said cover connected in series with said manually operable switch, said normally closed switch and manually operable switch being connected in said motor circuit in parallel with said normally open switch.

2. In a matrix drying mechanism, which includes a frame, a suction box on said frame having a perforated wall, a suction pump, a pipe line connecting said pump with said box, a motor operatively connected to said pump, heating means movable into operative proximity to said box, and control means for said heating means; means interposed between the box and the pump to regulate the degree of suction produced in said box when the pump is operating, said means comprising a springloaded valve set to open when the suction in said pipe line exceeds a predetermined value, an adjustable bleeder valve connected to said pipe line, a relief valve adapted to be opened and closed for relatively low and high suctions in said box, and spring means normally holding said relief valve open.

3. Mechanism as described in claim 2, including also a manifold located adjacent to an edge of said suction box, and a pipe connecting said manifold with said bleeder valve.

4. Matrix drying mechanism comprising a frame, a suction box on said frame, said box having a perforated top, a fine mesh wire screen fitted against said perforated top, a suction pump connected to said box to draw air therefrom, a normally open relief valve communicating with the connection between the pump and box, means for closing said valve to increase the suction in said box, a cover member hinged to said frame to swing up to an open position and down to a closed position over said box, a counterweight adapted to swing said cover member to its open position, latch means for holding said cover member in its closed position, a solenoid energizable to actuate said latch means to release said cover member, heating means carried by said cover member and movable thereby into proximity to said screen, an electric motor operatively connected to said suction pump, a normally open switch for controlling said motor, a second normally open switch for controlling said heating means, means operable by closing movement of said cover member for closing said switches and by opening movement of said cover member for opening said switches, timing mechanism operating in response to closing movement of said cover member to energize said latch releasing solenoid at the end of a predetermined time interval, and a second timing mechanism for closing said relief valve at the end of a predetermined interval following a closing of said cover member.

5. Matrix drying mechanism comprising a frame, a suction box on said frame, said box having a perforated top, a fine mesh wire screen fitted against said perforated top, a suction pump connected to said box to draw air therefrom, a normally open relief valve communicating with the connection between the pump and box, means for closing said valve to increase suction in said box, a cover member hinged to said frame to swing up to an open position and down to a closed position over said box, a counterweight adapted to swing said cover member to its open position, latch means for holding said cover member in its closed position, a solenoid energizable to actuate said latch means to release said cover member, heating means carried by said cover member and movable thereby into proximity to said screen, an electric motor operatively connected to said suction pump, a normally open switch for controlling said motor, a second normally open switch for controlling said heating means, means operable by closing movement of said cover member for closing said switches and by opening movement of said cover member for opening said switches, timing mechanism operating in response to closing movement of said cover member to energize said latch releasing solenoid at the end of a predetermined time interval, a second timing mechanism for closing said relief valve at the end of a predetermined interval following a closing of said cover member, and a third timing mechanism for shutting off the heating means at the end of a predetermined interval following a closing of said cover member.

8 7/38 Lougee 34-53 10/4-5 Preston 34-53 8/50 Baker 34-146 8/51 Messinger 219-19 11/52 Finzer 34-146 10/53 Elgar 219-19 12/55 Imshaug 34-146 8/57 Ushakotf 34-143 9/58 Worst 34-48 FOREIGN PATENTS 6/45 Denmark.

NORMAN YUDKOFF, Primary Examiner. CHARLES OCONNELL, BENJAMIN BENDETT,

Examiners. 

1. MATRIX DRYING MECHANISM COMPRISING A FRAME, A SUCTION BOX ON SAID FRAME HAVING A PERFORATED WALL, A WIRE SCREEN FITTED ON SAID PERFORATED WALL, A COVER MEMBER HINGED TO SAID FRAME AND SWINGABLE FROM AN OPEN POSITION TO A CLOSED POSITION OVER SAID SCREEN, A PUMP FOR DRAWING AIR FROM SAID BOX, A MOTOR OPERATIVELY CONNECTED TO SAID PUMP, A CIRCUIT CONNECTING SAID MOTOR TO A SOURCE OF POWER, A NORMALLY OPEN MICROSWITCH IN SAID CIRCUIT, SAID SWITCH BEING CLOSABLE BY CLOSING MOVEMENT OF SAID COVER, A MANUALLY OPERABLE STARTER SWITCH ON SAID FRAME, A NORMALLY CLOSED MICROSWITCH OPERABLE BY CLOSING MOVEMENT OF SAID COVER CONNECTED IN SERIES WITH SAID MANUALLY OPERABLE SWITCH, SAID NORMALLY CLOSED SWITCH AND MANUALLY OPERABLE SWITCH BEING CONNECTED IN SAID MOTOR CIRCUIT IN PARALLEL WITH SAID NORMALLY OPEN SWITCH. 